Coupled strings interact through a shared non-rigid bridge modeled as a single shared loss filter

In most stringed instruments, strings are attached to a common bridge. If the bridge is non-rigid, vibration energy from one string transfers to others. In a digital waveguide model, coupling is implemented by sharing the bridge’s loss filter across all string models: each string’s delay line feeds into a common filter (the bridge model), and the filtered signal distributes back to all strings. Because the bridge handles losses for all strings, the individual string models can remove their own loss filters, simplifying the design. The amount of coupling (bridge compliance) determines how much energy transfers between strings and how quickly each string damps the others.

Examples

Nord Modular coupled-strings patch: two delay lines share one bridge filter. Plucking one string causes sympathetic resonance in the other through the shared filter path.

Assessment

Explain what sound artifact would occur if the bridge was infinitely stiff (r=0 at bridge). Describe one musical scenario where coupled-string modeling produces a noticeably different sound than independent-string modeling.